Timing, equilibrium-line altitudes and climatic implications of two early-Holocene glacier readvances during the Erdalen Event at Jostedalsbreen, western Norway

Abstract

Following the Younger Dryas, the first evidence of glacial activity in southern Norway in response to climatic change occurred during the early Holocene, when terminal moraines from the Erdalen Event formed beyond the position of later ‘Little Ice Age’ moraines. In front of present outlet glaciers on both sides of the Jostedalsbreen ice cap, sets of pre-‘Little Ice Age’ marginal moraines have been morphostratigraphically corre lated with the Erdalen Event. The lithostratigraphy in a peat bog at Hellemyrane in Jostedalen, western Norway, provides firm evidence for a two-phase Erdalen Event associated with two glacier readvances of Nigardsbreen at the Preboreal/Boreal transition. Radiocarbon dates from the peat bog give age estimates for the two phases: the first Erdalen Event readvance took place between 10 100 and 10 050 cal. BP, while the second occurred close to 9700 cal. BP. The lowering of the equilibrium-line altitude (ELA) during these readvances is estimated using the ‘Little Ice Age’ ratio (LR) approach to be about 230 m and 215 m, respectively. The first readvance is attributed to an increase in winter precipitation, while the second readvance may have been primarily caused by a marked drop in summer temperature which reactivated already existing ice masses.

Non-linear regime shifts in Holocene Asian monsoon variability: potential impacts on cultural change and migratory patterns

“…50 globally distributed climate records from different kinds of archives (glacier fluctuations, ice cores, marine sediments), for which they coined the term rapid climate change (RCC) episodes. These changes appeared globally in a coherent way and were sufficiently abrupt to affect early human societies (deMenocal, 2001;Haberle and David, 2004). In fact, several of the identified RCC episodes can be attributed to the timing of major disruptions of civilisation (Cullen et al, 2000;Drysdale et al, 2006;Fleitmann et al, 2008;Baldini et al, 2002;Berkelhammer et al, 2012).…”

“…Over approximately the last two decades, this picture has, however, distinctively changed due to the identification of large-scale regional and even global climate episodes, which have interrupted the generally reduced climate variability and have lasted for several decades to centuries (Wanner et al, 2008). The climatic perturbations found during the Holocene are potentially relevant factors for the development of complex human societies and their behaviour (deMenocal, 2001). Investigating marine records from the North Atlantic Ocean, Bond et al (1997Bond et al ( , 2001 were the first to provide evidence of a persistent cycle of ice-rafted debris in sedimentary sequences.…”

Reconstruction of former glacier equilibrium-line altitudes based on proglacial sites: an evaluation of approaches and selection of sites

“…(e.g. Dahl and Nesje, 1994;Dahl et al, 2002). Whenever the glacier is in an advanced position beyond the local watershed, glacier-meltwater-induced sediments may be deposited at the proglacial site, while only organic sediments accumulate when the glacier is behind the local watershed.…”

“…5), the traditional ways to find former ELAs include the median elevation of glaciers (MEG), the toe-to-headwall ratio (THAR), accumulation area ratio (AAR), and the balance ratio method (see Nesje and Dahl, 2000, and references therein). In cases when only sparse remnants of marginal moraines are available, Dahl et al (2002) introduced a new technique termed the Little Ice Age ratio to estimate the ELA of glacier advances predating the Little Ice Age maximum. In addition to defining the modern ELA of existing glaciers, these techniques are important for calibrating reconstructed ELAs based on proglacial sites.…”

The long-term succession of cladoceran fauna and palaeoclimate forcing: A 14,600-year record from Plešné Lake, the Bohemian Forest

“…The third faunal zone (zone III; 282 to 273 cm; 10.5 to 10.3 kyr BP) represents only ∼250 years spanning the period between two Preboreal climatic oscillations dated to ∼10.5 and ∼10.2-10.1 kyr BP, respectively Dahl et al, 2002). These events, as well as the other two climate oscillations at the Pleistocene-Holocene transition (at ∼11.2 and ∼9.6 kyr BP), are identified by short-term decreases of C org concentrations in the otherwise increasing trend in the early Holocene (Fig.…”